The present invention relates to methods and compositions useful in subterranean operations, and more particularly, to novel uses of reactive surfactants in treating subterranean formations and/or proppant particulates.
Hydrocarbon wells are often located in subterranean formations that contain unconsolidated particulates (e.g., sand, gravel, proppant, fines, etc.) that may migrate out of the subterranean formation into a well bore and/or may be produced with the oil, gas, water, and/or other fluids produced by the well. The term “unconsolidated particulates,” and derivatives thereof, is defined herein to include loose particulates and particulates bonded with insufficient bond strength to withstand the forces created by the flow of fluids through the formation. Unconsolidated particulates may comprise, among other things, sand, gravel, fines, and/or proppant particulates in the subterranean formation, for example, proppant particulates placed in the subterranean formation in the course of a fracturing operation, among other purposes, to hold open conductive fractures created in that operation (e.g., forming a “proppant pack” within the fracture).
The presence of unconsolidated particulates in produced fluids may be undesirable in that, among other problems, the particulates may abrade pumping and other producing equipment and/or reduce the production of desired fluids from the well. Moreover, particulates that have migrated into a well bore, among other things, may clog portions of the well bore and/or a proppant pack, reducing the conductivity of the subterranean formation (i.e., the ability of fluids to flow through the formation).
Several different treatments are used in the art to control the migration of unconsolidated particulates in subterranean formations. As used herein, the term “treatment,” or “treated,” refers to any operation performed in conjunction with a desired function and/or for a desired purpose. The term “treatment,” or “treated,” does not imply any particular action. One such method involves placing a filtration bed containing gravel (e.g., a “gravel pack”) near the well bore to present a physical barrier to the transport of unconsolidated particulates with the production of desired fluids. Typically, such “gravel-packing operations” involve the pumping and placement of a quantity of certain particulate, into the unconsolidated subterranean formation in an area adjacent to a well bore. One common type of gravel-packing operation involves placing a screen in the well bore and packing the surrounding annulus between the screen and the well bore with gravel of a specific size designed to prevent the passage of formation sand. The screen is generally a filter assembly used to retain the gravel placed during the gravel-pack operation. A wide range of sizes and screen configurations are available to suit the characteristics of the gravel-pack sand used. To install the gravel pack, the gravel is carried to the formation in the form of a slurry by mixing the gravel with a viscous treatment fluid. Once the gravel is placed in the well bore, the viscosity of the treatment fluid is reduced, and it is returned to the surface. The resulting structure presents a barrier to migrating sand from the formation while still permitting fluid flow. However, the use of gravel packs and/or screens may exhibit problems such as screen plugging and screen erosion, or may be time-consuming and expensive to install.
Other methods used to control unconsolidated particulates in subterranean formations involve consolidating unconsolidated particulates into stable, permeable masses by applying a resin or a tackifying agent to the subterranean formation. The terms “consolidate,” “consolidating,” and derivatives thereof, are defined herein to include any process of stabilizing a portion of a subterranean formation, which may, at least in part, stabilize unconsolidated particulates such that they are bonded with sufficient bond strength to withstand the forces created by the flow of fluids through the formation and/or prevented from shifting or migrating. The particulates in these stable, permeable masses may be bonded with sufficient bond strength to withstand the forces created by the flow of fluids through the formation and/or prevented from shifting or migrating, but may still permit the flow of fluid(s) through the pore spaces of the mass. However, the use of conventional resins and tackifying agents may be problematic. For example, these treatments may require applying several different components (e.g., preflush fluids, afterflush fluids, catalysts, and the like) to the subterranean formation, which may add cost and complexity to the operation and/or require longer periods of time. Also, conventional multi-component treatments may not be practical due to the difficulty in determining if the entire interval has been treated with all of the components used.
Surfactants have been used heretofore in the art for many purposes, including stabilizing foams or emulsions, changing the wettability of surfaces, solubilizing certain materials, dewatering fluids, reducing the surface tension of fluids, increasing the viscosity of fluids, enhancing viscoelastic and rheological properties of fluids, and/or aiding in the placement of treatment fluids in subterranean formations. However, in some instances, conventional surfactants may destabilize a coating (e.g., resin or tackifying agent) on a surface within a subterranean formation or a surface of a proppant particulate, for example, by forming surfactant micelles within the coating and/or making the coating less dense. In other instances, it may be desirable to deposit molecules of a surfactant on a surface within a subterranean formation and/or a surface of a proppant particulate, for example, when the proppant particulate is to be treated with certain aqueous tackifying agents. However, molecules of conventional surfactants may not distribute themselves evenly along the coating, which may leave certain portions of a subterranean formation or a proppant particulate insufficiently treated with the surfactant for particular subterranean operations.